From 92f87182f2c617fd420832972b6d0ae4527301c8 Mon Sep 17 00:00:00 2001 From: Tom Lane Date: Tue, 3 Nov 2020 16:16:36 -0500 Subject: [PATCH] Guard against core dump from uninitialized subplan. If the planner erroneously puts a non-parallel-safe SubPlan into a parallelized portion of the query tree, nodeSubplan.c will fail in the worker processes because it finds a null in es_subplanstates, which it's unable to cope with. It seems worth a test-and-elog to make that an error case rather than a core dump case. This probably should have been included in commit 16ebab688, which was responsible for allowing nulls to appear in es_subplanstates to begin with. So, back-patch to v10 where that came in. Discussion: https://postgr.es/m/924226.1604422326@sss.pgh.pa.us --- src/backend/executor/nodeSubplan.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/src/backend/executor/nodeSubplan.c b/src/backend/executor/nodeSubplan.c index 9a706df5f0..152c7ae7eb 100644 --- a/src/backend/executor/nodeSubplan.c +++ b/src/backend/executor/nodeSubplan.c @@ -797,7 +797,15 @@ ExecInitSubPlan(SubPlan *subplan, PlanState *parent) sstate->planstate = (PlanState *) list_nth(estate->es_subplanstates, subplan->plan_id - 1); - /* ... and to its parent's state */ + /* + * This check can fail if the planner mistakenly puts a parallel-unsafe + * subplan into a parallelized subquery; see ExecSerializePlan. + */ + if (sstate->planstate == NULL) + elog(ERROR, "subplan \"%s\" was not initialized", + subplan->plan_name); + + /* Link to parent's state, too */ sstate->parent = parent; /* Initialize subexpressions */